tcpclient webrelay and control analog outputs - vb.net

Question

This is the first time that I have ever worked with networking in a program control webrelay. I was able to write my program with success... or so I thought. A couple of days ago I had a device drop off the network and my program "locked up". I know it did not truly lock up. I did some debugging and found out that what is happening is that when the tcpclient throws an exception, it just stops running any code after it. This causes my program to stop updating because of a timer that is never restarted and I con't control analog Outputs.
Public Class ControlPanelX317
Private SQL As New SQLControl
Private Sub ControlPanelX317_Load(sender As Object, e As EventArgs) Handles MyBase.Load
LoadControlsX317()
End Sub
'Dislay Conrol
'__________________________________________________________________________________________________________________________________________________________________________
Private Sub LoadControlsX317()
Dim loadqry As String = "SELECT * FROM controlsX317 WHERE controlsX317.ValueVoltageID = '" & 1 & "' "
Dim SQLCmd As New SqlCommand(loadqry, Sql.SQLCon)
If Sql.SQLCon.State = ConnectionState.Closed Then Sql.SQLCon.Open()
Dim reader As SqlDataReader = SQLCmd.ExecuteReader
While reader.Read = True
txt_S1_VolueVoltage.Text = reader("S1VolueVoltage")
txt_S2_VolueVoltage.Text = reader("S2VolueVoltage")
txt_S3_VolueVoltage.Text = reader("S3VolueVoltage")
txt_S4_VolueVoltage.Text = reader("S4VolueVoltage")
End While
SQLCmd.Dispose()
reader.Close()
Sql.SQLCon.Close()
End Sub
Private Sub btn_Save_ValueVoltage_Click(sender As Object, e As EventArgs) Handles btn_Save_ValueVoltage.Click
If txt_S1_VolueVoltage.Text > 10 Then
MsgBox("Max Voltage is 10V")
txt_S1_VolueVoltage.Clear()
Exit Sub
End If
If txt_S2_VolueVoltage.Text > 10 Then
MsgBox("Max Voltage is 10V")
txt_S2_VolueVoltage.Clear()
Exit Sub
End If
If txt_S3_VolueVoltage.Text > 10 Then
MsgBox("Max Voltage is 10V")
txt_S3_VolueVoltage.Clear()
Exit Sub
End If
If txt_S4_VolueVoltage.Text > 10 Then
MsgBox("Max Voltage is 10V")
txt_S4_VolueVoltage.Clear()
Exit Sub
End If
If txt_S1_VolueVoltage.Text <> "" Then
Dim UpdateValueVoltage As String = "UPDATE controlsX317 SET S1VolueVoltage='" & txt_S1_VolueVoltage.Text & "', S2VolueVoltage='" & txt_S2_VolueVoltage.Text & "',
S3VolueVoltage='" & txt_S3_VolueVoltage.Text & "', S4VolueVoltage='" & txt_S4_VolueVoltage.Text & "'
WHERE ValueVoltageID ='" & 1 & "' "
If SQL.DataUpdate(UpdateValueVoltage) = 0 Then
MsgBox("The Sysytem could not be found!!! ")
Else
MsgBox("VolueVoltage successfully changed")
End If
Else
MsgBox("You must restart a Sysytem")
End If
End Sub
Private Sub btn_S1_SetVoltage_Click(sender As Object, e As EventArgs) Handles btn_S1_SetVoltage.Click
lbl_S1_AnalogOutput.Text = Val(txt_S1_VolueVoltage.Text) * Val(txt_S1_ControlViltage.Text / 100) & "V"
End Sub
Private Sub btn_S2_SetVoltage_Click(sender As Object, e As EventArgs) Handles btn_S2_SetVoltage.Click
lbl_S2_AnalogOutput.Text = Val(txt_S2_VolueVoltage.Text) * Val(txt_S2_ControlViltage.Text / 100) & "V"
End Sub
Private Sub btn_S3_SetVoltage_Click(sender As Object, e As EventArgs) Handles btn_S3_SetVoltage.Click
lbl_S3_AnalogOutput.Text = Val(txt_S3_VolueVoltage.Text) * Val(txt_S3_ControlViltage.Text / 100) & "V"
End Sub
Private Sub btn_S4_SetVoltage_Click(sender As Object, e As EventArgs) Handles btn_S4_SetVoltage.Click
lbl_S4_AnalogOutput.Text = Val(txt_S4_VolueVoltage.Text) * Val(txt_S4_ControlViltage.Text / 100) & "V"
End Sub
'End Display Control
'_________________________________________________________________________________________________________________________________________________________________________
'Conection to WebRelay X317
'_________________________________________________________________________________________________________________________________________________________________________
Public Sub getWebRelayState()
Dim tcpClient As New TcpClient()
Dim port As Integer
Try
port = Convert.ToInt32(txtPort.Text)
tcpClient.Connect(txt_IPAddress.Text, port)
If tcpClient.Connected Then
'Create a network stream object
Dim netStream As NetworkStream = tcpClient.GetStream()
'If we can read and write to the stream then do so
If netStream.CanWrite And netStream.CanRead Then
'Send the on command to webrelay
Dim sendBytes As Byte() = Encoding.ASCII.GetBytes("GET /state.xml?noReply=0 HTTP/1.1" & vbCrLf & "Authorization: Basic bm9uZTp3ZWJyZWxheQ==" & vbCrLf & vbCrLf)
netStream.Write(sendBytes, 0, sendBytes.Length)
'Get the response from webrelay
Dim bytes(tcpClient.ReceiveBufferSize) As Byte
netStream.Read(bytes, 0, CInt(tcpClient.ReceiveBufferSize))
'Parse the response and update the webrelay state and input text boxes
Dim returndata As String = Encoding.ASCII.GetString(bytes)
'Parse out the relay state and input state
Dim array1 As Char() = returndata.ToCharArray()
Dim ana(4) As Integer
'Relay State found at index 66
If array1(66) = "1" Then
RelayState.Text = "ON"
Else
RelayState.Text = "OFF"
End If
'Input State found at index 94
If array1(94) = "1" Then
inputState.Text = "ON"
Else
inputState.Text = "OFF"
End If
End If
'Close the connection
tcpClient.Close()
End If
Catch ex As Exception
inputState.Text = "Error"
RelayState.Text = "Error"
'Disable the timer
TimerRelayRefresh.Enabled = False
End Try
End Sub
Private Sub sendRequest(ByVal val As String)
Dim tcpClient As New TcpClient()
Dim port As Integer
Try
'Disable the timer
TimerRelayRefresh.Enabled = False
port = Convert.ToInt32(txtPort.Text)
tcpClient.Connect(txt_IPAddress.Text, port)
If tcpClient.Connected Then
MsgBox("connection successful")
'Create a network stream object
Dim netStream As NetworkStream = tcpClient.GetStream()
'If we can read and write to the stream then do so
If netStream.CanWrite And netStream.CanRead Then
'Send the on command to webrelay
Dim sendBytes As Byte() = Encoding.ASCII.GetBytes("GET /state.xml?relayState=1 HTTP/1.1<CR><LF>" & vbCrLf & "Authorization: Basic bm9uZTp3ZWJyZWxheQ==<CR><LF><CR><LF>" & vbCrLf & vbCrLf)
netStream.Write(sendBytes, 0, sendBytes.Length)
'Get the response from webrelay
Dim bytes(tcpClient.ReceiveBufferSize) As Byte
netStream.Read(bytes, 0, CInt(tcpClient.ReceiveBufferSize))
'Parse the response and update the webrelay state and input text boxes
Dim returndata As String = Encoding.ASCII.GetString(bytes)
'Parse out the relay state and input state
Dim array1 As Char() = returndata.ToCharArray()
'Relay State found at index 66
If array1(66) = "1" Then
RelayState.Text = "ON"
Else
RelayState.Text = "OFF"
End If
'Input State found at index 94
If array1(94) = "1" Then
inputState.Text = "ON"
End If
Else
inputState.Text = "OFF"
End If
End If
'Enable the timer
TimerRelayRefresh.Enabled = True
Catch ex As Exception
inputState.Text = "Error"
RelayState.Text = "Error"
'Disable the timer
TimerRelayRefresh.Enabled = False
End Try
End Sub
Private Sub btn_ControlsX317_On_Click(sender As Object, e As EventArgs) Handles btn_ControlsX317_On.Click
sendRequest("1")
End Sub
Private Sub btn_ControlsX317_Off_Click(sender As Object, e As EventArgs) Handles btn_ControlsX317_Off.Click
sendRequest("0")
End Sub
Private Sub btn_ControlsX317_PULSE_Click(sender As Object, e As EventArgs) Handles btn_ControlsX317_PULSE.Click
sendRequest("2")
End Sub
'End Conetion
'_________________________________________________________________________________________________________________________________________________________________________
End Class